Maximizing soybean yields through managed inputs

Increasing commodity prices have placed tremendous pressure on farmers to increase their total production; however, land and input costs continue to rise in parallel with grain prices. These increased costs, prices and risks have changed the landscape for crop management.

With so much capital in agriculture, industry continues to develop new products to help farmers produce higher yields, yet very few products have been shown to significantly increase soybean yields. As a result of this, many farmers have begun to accept the notion that maximizing soybean yields requires the synergistic effects of multiple products. Without proper evaluation, farmers risk choosing products that have little promise of increasing yields, and may instead experience reductions in profits, and increasing chances of pest resistance and environmental degradation.

In my role as a University of Minnesota Extension Soybean Agronomist, I have been leading a national project to investigate soybean yield enhancement through high-input production systems. This unique project has been supported with soybean checkoff dollars through the United Soybean Board, and involves research teams in Minnesota, Iowa, Michigan, Kentucky, Arkansas and Louisiana.

Another goal of the project was to find ways to maximize soybean returns through the optimization of soybean seeding rates, and to examine the effects of annual fertilization versus the traditional biennial fertilization that occurs in most corn-soybean rotations. All of these studies were carried out in at least three locations per state.

The high-input study has been termed the "Kitchen Sink" study because researchers threw any reasonable product at soybeans in order to elicit a yield response. Some of the inputs and technologies utilized in these trials included: superoptimal seeding rates, narrow row spacing, seed inoculants, fungicide and insecticide seed treatments, additional soil fertilizers, foliar fertilizers, and foliar fungicides. Products were applied in systems that included all possible products and treatments where single products were 'knocked-out' to identify products that might play an obligatory role in the high yield treatments. In addition, early-season and late-season management systems were utilized to evaluate different hypothetical management strategies.

The 'kitchen sink' treatments did yield four to six bushels more than control treatments, but identifying responsible products was more difficult than expected. Inoculants, seed treatments, extra soil fertility, and foliar fertilizer treatments did not appear to be critical components of the kitchen sink treatment. Only when foliar fungicide was removed, did yields drop significantly.

Perhaps the most interesting and important finding of this work involved the oldest technology tested: row spacing. Not only did the narrow rows produce significantly greater yields than did the wide rows, but this factor appeared to be the single most important factor tested. In fact, producers considering moving back to wide rows should know that, in order to maintain yield parity with narrow row systems, they will be required to invest significant dollars into yield-promoting factors such as foliar fungicides.

Corn and Soybean Digest has developed an Apple and Android app, based on this research, to help farmers evaluate the cost of inputs relative to their expected yield response. Please search for "Extreme Beans" to find the app at iTunes or the Android Market.